In most front wheel drive vehicles, a phenomenon known as “torque steer” is experienced. Torque steer is a vehicle steering effect resulting from a difference in braking force (braking torque) and/or driving force (traction or driving torque) between left and right steered road wheels. In order to eliminate or cancel the torque steer effect, a steering torque value resulting from torque steer must be compensated for. Generally, on automotive vehicles employing electric power steering devices, torque steer is compensated for by summing the steering torque value corresponding to torque steer to a steering assistance torque command value, thus effectively suppressing an undesirable steering-wheel pull (steering-wheel pulling power) in clockwise or anticlockwise directions, that is, positive or negative fluctuations in steering-wheel rotation angle occurring owing to torque steer. Such torque-steer compensation technologies have been disclosed in U.S. Pat. No. 6,154,696 (corresponding to Japanese Patent Provisional Publication No. 11-129927) and U.S. Pat. No. 6,032,755 (corresponding to Japanese Patent Provisional Publication No. 9-207802). As is generally known, in heavy vehicles employing high-power engines, there is an increased tendency for torque steer to occur. However, assuming that the previously-discussed electric-power-steering device equipped torque-steer compensation system, which uses a summed value of a steering assistance torque command value and a steering torque value required to cancel torque steer, is applied to such heavy vehicles, there are several drawbacks, such as a lack of steering assistance torque owing to the limited line-source voltage, a large-sized electric motor, or an increased weight of the electric power steering device. Thus, an electric power steering device is unsuitable to heavy vehicles employing high-power engines. On automotive vehicles employing braking/driving force control systems (or active torque split control systems) capable of individually controlling braking force and/or driving force between left and right road wheels, when there is an excessive difference in driving force between left and right steered road wheels, the control system generally acts to limit or decreasingly compensate for the engine power output (corresponding to the summed torque value of driving torque applied to the left steered wheel and driving torque applied to the right steered wheel) in order to avoid the torque steer from excessively develop. This deteriorates the acceleration performance.